Multi-Frequency Air-to-Ground Channel Measurements and Analysis for UAV Communication Systems

Zhuangzhuang Cui,Francois Quitin,Zhangdui Zhong,Ke Guan,Cesar Briso-Rodriguez

doi:10.1109/access.2020.2999659

Zhuangzhuang Cui, Francois Quitin + Show 3 more

Open Access

https://doi.org/10.1109/access.2020.2999659

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Abstract

In order to implement unmanned aerial vehicle (UAV)-based wireless communications, a better understanding of wireless channels and the corresponding channel characterizations are critical. In this paper, air-to-ground (AG) channel measurements are carried out at some candidate frequencies, i.e., 1 GHz, 4 GHz, 12 GHz, and 24 GHz. With measurement data, the crucial channel parameters are comprehensively analyzed. Firstly, based on the channel model in the 3rd Generation Partnership Project (3GPP), the essential coefficients for modeling path loss, including path loss exponents (PLEs) and height-dependent factors, are obtained for AG channels. Then, a novel autocorrelation model for shadow fading is proposed. Besides, the small-scale fading is statistically analyzed, where the log-logistic distribution is found as the best fit among popular distributions. Moreover, the second-order statistical characteristics, including the level crossing rate (LCR) and average fade duration (AFD), are extracted to describe in-depth the fading behavior. Overall, the results and findings in this paper are essential for realizing reliable communications in AG wireless systems.

Highlights

Unmanned aerial vehicle (UAV) has drawn much attention in wireless communications since it has been regarded as an essential enabler for realizing broad coverage and high-speed data rates [1]
At the Tx end, the unmanned aerial vehicle (UAV)-integrated test Tx is equipped with a Rugged Surface Mount-Wideband High Frequency (RMWHF) antenna with 3 dBi gain for 4 GHz and three λ/4 monopole antennas with 5.19 dBi gain for 1 GHz, 12 GHz, and 24 GHz, respectively
For the large-scale parameters of AG channels, the mean path loss exponents (PLEs) are 2.470 and 3.666 for LOS and NLOS case, respectively, which are slightly different from the 3rd Generation Partnership Project (3GPP) parameters (i.e., 2.200 and 3.908 for LOS and NLOS case)

Summary

INTRODUCTION

Unmanned aerial vehicle (UAV) has drawn much attention in wireless communications since it has been regarded as an essential enabler for realizing broad coverage and high-speed data rates [1]. Z. Cui et al.: Multi-Frequency AG Channel Measurements and Analysis for UAV Communication Systems layer of the space-air-ground integrated network (SAGIN), which needs to realize connections with ground terminals, as well as with satellites that generally work in the C-band, Ku-band, K-band [5]. By comparing results from multi-frequency measurements, the frequency-dependent characteristics can be analyzed and modeled Another essential concern in AG channel modeling is the impact of the UAV altitude on the propagation channel. Amorim et al proposed a height-dependent log-distance α − β − γ path loss model by means of the fitting of measurement data at 1.5 m, 15 m, 30 m, 60 m and 120 m [13].

AG CHANNEL MEASUREMENTS

DATA ACQUISITION AND PROCESSING

SMALL-SCALE FADING AND DEPTH

SECOND-ORDER STATISTICAL CHARACTERISTICS

CONCLUSION